vk: add patchable smoothing threshold

Automatically smooth normals between surfaces with normals less than 45
degrees off.

Can be adjusted from map.bsp.patch file like this (e.g. to 50 degrees):
```
{
	"_xvk_smoothing_threshold" "50"
}
```

ref/vk/shaders/denoiser.comp

@@ -41,6 +41,7 @@ const int INDIRECT_SCALE = 2;
 //#define DEBUG_TEXTURE normals_gs
 //#define DEBUG_TEXTURE emissive
 //#define DEBUG_TEXTURE light_point_diffuse
+//#define DEBUG_NORMAL
 
 // Blatantly copypasted from https://www.shadertoy.com/view/XsGfWV
 vec3 aces_tonemap(vec3 color){
@@ -197,7 +198,7 @@ void main() {
 	//imageStore(out_dest, pix, vec4(fract(imageLoad(position_t, pix).rgb/10.), 0.)); return;
 	//imageStore(out_dest, pix, vec4(fract(imageLoad(geometry_prev_position, pix).rgb/50.), 0.)); return;
 
-#if 0
+#if defined(DEBUG_NORMAL)
 	vec3 geometry_normal, shading_normal;
 	readNormals(pix, geometry_normal, shading_normal);
 	//imageStore(out_dest, pix, vec4(.5 + geometry_normal * .5, 0.)); return;

ref/vk/vk_brush.c

@@ -807,16 +807,10 @@ static qboolean shouldSmoothLinkSurfaces(const model_t* mod, int surf1, int surf
 	getSurfaceNormal(mod->surfaces + surf2, n2);
 
 	// TODO patch filtering
-	const float threshold = .7f;
-	return DotProduct(n1, n2) > threshold;
+	const float dot = DotProduct(n1, n2);
+	DEBUG("Smoothing: dot(%d, %d) = %f (t=%f)", surf1, surf2, dot, g_map_entities.smoothing_threshold);
 
-	/*
-	if (
-	((cedge->surfs[0] == 743 || cedge->surfs[1] == 743) &&
-	 (cedge->surfs[0] == 741 || cedge->surfs[1] == 741)) ||
-	((cedge->surfs[0] == 367 || cedge->surfs[1] == 367) &&
-	 (cedge->surfs[0] == 404 || cedge->surfs[1] == 404))) {
-	*/
+	return dot >= g_map_entities.smoothing_threshold;
 }
 
 static int lvFindValue(const linked_value_t *li, int count, int needle) {

ref/vk/vk_mapents.c

@@ -570,6 +570,8 @@ static void parseEntities( char *string, qboolean is_patch ) {
 							addPatchSurface( &values, have_fields );
 						} else if (have_fields & Field__xvk_ent_id) {
 							patchEntity( &values, have_fields );
+						} else if (have_fields & Field__xvk_smoothing_threshold) {
+							g_map_entities.smoothing_threshold = cosf(DEG2RAD(values._xvk_smoothing_threshold));
 						}
 					}
 					break;
@@ -676,6 +678,7 @@ void XVK_ParseMapEntities( void ) {
 	g_map_entities.single_environment_index = NoEnvironmentLights;
 	g_map_entities.entity_count = 0;
 	g_map_entities.func_walls_count = 0;
+	g_map_entities.smoothing_threshold = cosf(DEG2RAD(45.f));
 
 	parseEntities( map->entities, false );
 	orientSpotlights();

ref/vk/vk_mapents.h

@@ -26,6 +26,7 @@
 	X(19, vec2_t, _xvk_tex_offset, Vec2) \
 	X(20, vec2_t, _xvk_tex_scale, Vec2) \
 	X(21, string, model, String) \
+	X(22, float, _xvk_smoothing_threshold, Float) \
 
 /* NOTE: not used
 	X(22, int, rendermode, Int) \
@@ -128,6 +129,8 @@ typedef struct {
 	// TODO find out how to read this from the engine, or make its size dynamic
 //#define MAX_MAP_ENTITIES 2048
 	xvk_mapent_ref_t refs[MAX_MAP_ENTITIES];
+
+	float smoothing_threshold;
 } xvk_map_entities_t;
 
 extern xvk_map_entities_t g_map_entities;